I think it means you have a normal level of RF - rheumatoid factor, in your blood. Sometimes referred to as being "RF negative". 80% of people with rheumatoid arthritis are RF positive.
This doesn't rule out or in any disorder but is another clue for your doctor to use to determine the exact nature of your condition.
Check with your doc, "normal" ranges vary across the country lab to lab, but I think you're well within the normal normal.